In an innovative use of a former rock quarry, the Metropolitan Nashville Airport Authority (MNAA) today broke ground on what will be the largest geothermal lake plate cooling system in North America. The historic sustainability project is expected to be completed in summer 2016.

Located east of Donelson Pike and Nashville International Airport (BNA) Runway 2R/20L is the former 43-acre Hoover rock quarry, with an average depth of 150 feet, containing approximately 1.5 billion gallons of water. At a depth of 50 feet, the water is 50 degrees Fahrenheit year round.

The project takes advantage of that cool temperature by circulating water through geothermal heat exchangers submerged in the quarry to the airport terminal's central plant, providing cooling for the entire terminal. In addition to the geothermal system, the project will also allow for the use of the quarry water for landscape irrigation.

"This is a remarkable project for its scope, ingenuity and efficiency," said Rob Wigington, president and CEO of MNAA. "The Airport Authority is committed to making sustainability an integral part of our business model. Not because sustainability is easy-rather, it is often a complex process-but because the benefits to our airports, the region and our environment are overwhelmingly positive. This historic project will significantly reduce our electricity usage and potable water consumption, which will result in substantial annual utility savings. This is the very essence of sustainability."

The project is expected to reduce electricity usage by 6,000 kilowatts of peak demand and result in annual savings of 1.3 million kilowatt-hours and 30 million gallons of potable water. The utility savings to MNAA are expected to be more than $430,000 per year.

The project was developed and engineered by Energy Systems Group, Garver, and Smith Seckman Ried. The fast-track project is being delivered by Blakley Construction Services utilizing a design-build contracting method with design and construction support services being provided by Energy Systems Group, Garver Engineers, and Smith Seckman Ried.